1965

6.7

1977

6.8

1981

6.5

2005

6.5

1998

6.8

1974

7.9

1972

7.1

2004

6.5

2006

5.9

2013

6.6

1997

4.6

1955

6.0

1984

6.7

1989

7.4

2005

4.6

1996

6.3

2002

3.4

2007

6.9

1974

7.0

2011

6.6